Green thumbs emphasise the benefits of roof-top gardens

Horticultural researchers from the University of Melbourne are hoping a new study will inspire city-dwellers to turn their roofs green.

Researchers from the university's Burnley campus have been looking at what flora is the best to plant on the top of buildings in Australian cities.

The research, based on natural rocky outcrops supporting shallow soils, high temperatures and varying water levels, has been published in the Journal of Plant and Soil.

The team's study found succulent plants can survive for long periods of time without water.

But researchers discovered the ideal plants were not only drought-proof, but made good use of water after rainfall, to reduce storm-water run-off.

"When we tested different green roof plants, some of the rocky outcrop plants used 20 times more water than succulents when water was available," said Dr Claire Farrell, of the School of Land and Environment.

"It may seem improbable that a plant that uses a lot of water could also be drought tolerant, but these ensure optimal performance and resilience on green roofs," she said.

The school advocates green roofs as natural insulation for buildings, as well as a habitat for birds, lizards and insects.

Students at the Burnley campus will be able to obtain a specialist certificate in green roofs and walls, based on the research.

It is the only course of its type in Australia.

The university has displayed a specially-made freight container with a green roof at Melbourne's City Square this week.

It has now moved to the Carlton Gardens for the annual Melbourne International Flower and Garden Show at the weekend.

You have no doubt been hearing a lot about the Paris Agreement and know that it pertains to climate change, but are too embarrassed at this stage to ask for an overall explanation of what it's all about.